1,2-benzisothiazolin-3-one ("BIT") is an effective biocide. It is desirable to provide BIT as a liquid formulation for its intended use. Unfortunately, BIT has low solubility in water. It can be used in the form of an aqueous dispersion; however, BIT tends to settle out from a quiescent mixture, especially at low temperatures.
Liquid formulations of BIT in amines have been disclosed. For example, U.K. Pat. No. 1,191,253 discloses solutions of BIT in water and two or more amine salts. U.K. Pat. No. 1,330,531 discloses solutions of BIT, in the form of its amine salt, in at least one amine and, optionally, water. U.S. Pat. No. 4,923,887 discloses liquid formulations of BIT with ethoxylated (coconut alkyl)-amine, water, alcohols, 1,2-propylene glycol, dipropylene glycol, polyglycols, ether of glycols, or their mixture, as co-solvent. U.S. Pat. No. 5,276,047 discloses liquid formulations of BIT with triamines and triamine mixtures, water, glycols and alkylglycol ethers.
BIT formulations that include amines may not be suitable for certain applications. Amines are typically volatile and have strong unpleasant odors. Amines are generally unacceptable for indirect food contact applications. Amines can cause yellowing of certain water-base latices. The aforementioned amine solutions of BIT may not be suitable for use as biocides for in-can preservation.
U.S. Pat. No. 4,188,376 discloses liquid formulations of alkali metal salts of crude BIT with dipropylene glycol, tripropylene glycol, polyethylene glycols (having a molecular weight of 300), certain alcohols, lower alkyl carbitols and mixtures of the foregoing, with water. Alcohols, lower alkyl carbitols and dipropylene glycol are volatile and are associated with certain odors. Further, BIT formulations containing tripropylene glycol and polypropylene glycol suffer from poor low temperature stability; co-solvents such as propylene glycol or dipropylene glycol must be used to prevent BIT precipitation.
Thus, there is a need for a liquid formulation of BIT that has good stability, even under low temperature storage conditions, has very low VOC content and is suitable for a wide range of applications.